First, for all those who have never heard of it- Yes, there is such a thing as installing longer wheel studs. However, it is not something that is commonly done on stock vehicles and even when using an aftermarket rim. Longer wheel studs are more common in the world of racing; a longer stud helps for two reasons in a racing application- it allows easier placement of a wheel on to the hub/axle flange during quick change pit stops, and maybe more importantly also allows the first 1/2"-1" of thread on the stud to be smooth down (like a dowel pin). Then just like in a NASCAR pit stop, wheels with lug nuts already glued on the rim will slide over the smooth portion of the longer stud and make it easy for an impact gun to index the lug nut thread to the wheel stud thread while minimizing chance of crossing them. Ok, enough being Captain Obvious and preaching to the choir.
Now let's address some things that you may be able to do without installing longer wheel studs; lug nuts do come in two basic types-
1) tapered- this type has a conical taper on the outside of the threaded base side. You appear to have these, this is what helps to center a wheel on an axle flange.
2) flange- this type has a flat base where the threads begin. These are not nearly as common and typically on specialty wheels.
It's hard to tell with your wheels, but it's not impossible that you may need flange type lug nuts with the flat face, not the conical tapered face.
If you decide it is certain that you need longer wheel studs, DO NOT GO CHEAP! Use a quality stud like an ARP, they are the standard for these kinds of fasteners/bolts
http://www.summitracing.com/search/product-line/arp-wheel-studs
http://www.jegs.com/p/JEGS-Performance-Products/JEGS-Wheel-Studs/1224592/10002/-1